Breaker bar

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Breaker bar

A breaker bar (also known as a power bar) is a long non-ratcheting bar that is used with socket wrench-style sockets. They are used to break loose very tight fasteners because their additional length allows the same amount of force to generate significantly more torque than a standard length socket wrench. [1] : 1, 3  Their use prevents damage to the ratcheting mechanism of a socket wrench. Often, after the first half turn, the fastener is loose enough to be turned with a socket wrench.

Contents

Function

The long handle on breaker bars compared to shorter wrenches allows a larger torque to be generated with the same amount of force. It is effectively a lever, one of the simple machines. [2] Also, the absence of a ratcheting mechanism makes a breaker bar considerably stronger than a ratchet. This allows greater torque to be applied to a fastener without the tool failing. A breaker bar can be improvised by inserting a wrench into a length of metal pipe to increase the available torque by using the pipe to extend the effective length of the breaker bar. A pipe used for this purpose is called a cheater bar or snipe.

Materials

A breaker bar is able to create a larger amount of rotational force compared to a standard socket wrench. A standard breaker bar is strong enough to allow the user to apply up to 2500 pound-feet of torque without breaking the bar. [3] A high-end 1/2" socket wrench can withstand a maximum of 500 pound-feet of torque. [4] Since the breaker bar creates and withstands a larger amount of torque it is often used in place of a standard socket wrench to break loose tight-fitting fasteners. To be able to create these high torque numbers breaker bars have to be made out of a metal of adequate strength properties.

High-quality breaker bars are typically made of chromium-vanadium steel (AISI 6150). [5] Chromium-vanadium steel is known for its high strength, excellent toughness, and shock resistance. [6] Chromium vanadium steel has a yield strength at 0.2% offset of 84.0 kilo-pound per square inch (KSI). Meaning, chromium-vanadium steel can withstand up to 84 KSI before it begins to yield. [7] If the steel is unloaded before the yield point it is elastic and the material will return to its original configuration. Because of its high yield strength and shock resistance, standard socket wrenches, and breaker bars are fashioned from this material. In addition to its high yield strength, chromium-vanadium steel provides resistance to abrasion, oxidation, and corrosion making it a viable material for the production of tools. [6]

Physics

Rotational force, also known as torque, varies depending on where the force is applied. If the force is applied closer to the object the torque is smaller than if the same amount of force is applied further from the object. A breaker bar creates a larger force due to the amount of torque that can be applied through a longer handle versus a shorter one. A lever arm, also known as a moment arm, is an important factor to consider when measuring the torque of a breaker bar. Having a longer lever arm creates a larger surface area for the force to be applied, which increases rotational force. Surface area is the measure of the total amount of area an object occupies. When the radius of the moment arm is increased, the surface area is proportionally increased. [8]

The concept that torque is related to a larger moment arm is shown in the torque equation. The torque equation can be written as follows: 𝜏 (Torque) = F (Force) x r (Radius). Since the force applied is multiplied by the radius of the moment arm, having a larger radius subsequently creates a larger torque. This makes the torque value on the point of rotation much greater as the size of the handle or moment arm increases. [9]

Related Research Articles

<span class="mw-page-title-main">Torque</span> Turning force around an axis

In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force. The symbol for torque is typically , the lowercase Greek letter tau. When being referred to as moment of force, it is commonly denoted by M. Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point; for example, driving a screw uses torque, which is applied by the screwdriver rotating around its axis. A force of three newtons applied two metres from the fulcrum, for example, exerts the same torque as a force of one newton applied six metres from the fulcrum.

<span class="mw-page-title-main">Screwdriver</span> Hand tool used for turning screws

A screwdriver is a tool, manual or powered, used for turning screws.

A torque wrench is a tool used to apply a specific torque to a fastener such as a nut, bolt, or lag screw. It is usually in the form of a socket wrench with an indicating scale, or an internal mechanism which will indicate when a specified (adjustable) torque value has been reached during application.

<span class="mw-page-title-main">Torx</span> Screw drive with 6-lobed star-shaped flower-petal pattern

Torx is a trademark for a type of screw drive characterized by a 6-point star-shaped pattern, developed in 1967 by Camcar Textron. A popular generic name for the drive is star, as in star screwdriver or star bits. The official generic name, standardized by the International Organization for Standardization as ISO 10664, is hexalobular internal. This is sometimes abbreviated in databases and catalogs as 6lobe. Torx Plus,Torx Paralobe and Torx ttap are improved head profiles.

<span class="mw-page-title-main">Carbon steel</span> Steel in which the main interstitial alloying constituent is carbon

Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states:

<span class="mw-page-title-main">Fastener</span> Hardware device that mechanically joins or affixes two or more objects together

A fastener or fastening is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or dismantled without damaging the joining components. Steel fasteners are usually made of stainless steel, carbon steel, or alloy steel.

<span class="mw-page-title-main">Bolted joint</span> Mechanical joint secured by a threaded fastener

A bolted joint is one of the most common elements in construction and machine design. It consists of a male threaded fastener that captures and joins other parts, secured with a matching female screw thread. There are two main types of bolted joint designs: tension joints and shear joints.

<span class="mw-page-title-main">Socket wrench</span> Lever with interchangeable socket heads to grip or turn a bolt or nut

A socket wrench is a type of spanner that uses a closed socket format, rather than a typical open wrench/spanner to turn a fastener, typically in the form of a nut or bolt.

<span class="mw-page-title-main">Cheater bar</span> Improvised breaker bar

A cheater bar, snipe, or cheater pipe is an improvised breaker bar made from a length of pipe and a wrench (spanner).

<span class="mw-page-title-main">Torsion (mechanics)</span> Twisting of an object due to an applied torque

In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed in newton metres (N·m) or foot-pound force (ft·lbf). In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius.

<span class="mw-page-title-main">Impact wrench</span> Socket wrench power tool

An impact wrench is a socket wrench power tool designed to deliver high torque output with minimal exertion by the user, by storing energy in a rotating mass, then delivering it suddenly to the output shaft. It was invented by Robert H. Pott of Evansville, Indiana.

<span class="mw-page-title-main">Impact driver</span> Hand tool for loosening threaded fasteners, with a powerful intermittent action

An impact driver is a tool that delivers a strong, sudden rotational force and forward thrust. The force can be delivered either by striking with a hammer in the case of manual impact drivers, or mechanically in the case of powered impact drivers.

<span class="mw-page-title-main">Screw mechanism</span> Mechanism that converts motion, and forces, from rotational to linear

The screw is a mechanism that converts rotational motion to linear motion, and a torque to a linear force. It is one of the six classical simple machines. The most common form consists of a cylindrical shaft with helical grooves or ridges called threads around the outside. The screw passes through a hole in another object or medium, with threads on the inside of the hole that mesh with the screw's threads. When the shaft of the screw is rotated relative to the stationary threads, the screw moves along its axis relative to the medium surrounding it; for example rotating a wood screw forces it into wood. In screw mechanisms, either the screw shaft can rotate through a threaded hole in a stationary object, or a threaded collar such as a nut can rotate around a stationary screw shaft. Geometrically, a screw can be viewed as a narrow inclined plane wrapped around a cylinder.

<span class="mw-page-title-main">Hydraulic torque wrench</span> Power tool designed to exert torque on a fastener

A hydraulic torque wrench is a power tool designed to exert torque on a fastener to achieve proper tightening or loosening of a connection through the use of hydraulics. A torque wrench is applied to the nut either directly or in conjunction with an impact socket. Hydraulic torque wrenches apply a predetermined, controlled amount of torque to a properly lubricated fastener.

<span class="mw-page-title-main">Screw</span> Type of fastener characterized by a thread wrapped around a cylinder core

A screw is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to the head. The most common uses of screws are to hold objects together and there are many forms for a variety of materials. Screws might be inserted into holes in assembled parts or a screw may form its own thread. The difference between a screw and a bolt is that the latter is designed to be tightened or released by torquing a nut.

<span class="mw-page-title-main">Nut (hardware)</span> Type of fastener with a threaded hole

A nut is a type of fastener with a threaded hole. Nuts are almost always used in conjunction with a mating bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads' friction, a slight stretching of the bolt, and compression of the parts to be held together.

<span class="mw-page-title-main">Torque multiplier</span>

A torque multiplier is a tool used to provide a mechanical advantage in applying torque to turn bolts, nuts or other items designed to be actuated by application of torque, particularly where there are relatively high torque requirements.

<span class="mw-page-title-main">Bolt (fastener)</span> Threaded fastener with an external male thread requiring a matching female thread

A bolt is an externally helical threaded fastener that fastens objects with unthreaded holes together. This is done by applying a twisting force (torque) to a matching nut. The bolt has an external male thread requiring a matching nut with a pre-formed female thread. Unlike a screw, which holds objects together by the restricting motion parallel to the axis of the screw via the normal and frictional forces between the screw's external threads and the internal threads in the objects to be fastened, a bolt prevents that linear motion via the frictional and normal forces between the bolt's external threads and the internal threads of the matching nut, which can be tightened by applying a torque which moves the nut linearly along the axis of the bolt and compresses the objects to be fastened.

Amount of the no-load tension in the bolted joint (preload) greatly affects the reliability of the joint. Multiple techniques exist for preload control to ensure that the tension in the bolt is close to the one specified in the design :

References

  1. ↑ U.S. Patent 4,811,638 (1989). Retrieved 3 May 2010
  2. ↑ "Simple Machines". hyperphysics.phy-astr.gsu.edu. With a lever, one can obtain a multiplication of force, but of course not a multiplication of energy. The multiplication of force can be seen to arise from the equilibrium of torques, where an input force Fe with a long lever arm Le can balance a larger resistance force Fr with a short lever arm Lr.
  3. ↑ Smith, John (6 January 2022). "Can You Use A Torque Wrench As A Breaker Bar?". Clever Handymen. Retrieved 14 February 2023.
  4. ↑ Dehner, Robert S. (2 September 2022). "How Much Torque Can A Drive Take? (1/2, 1/4, 3/8 Drive) [Analyzed]". powertoolinstitute.net. Retrieved 14 February 2023.
  5. ↑ Sui, Jason (3 March 2020). "Top 10 Best Breaker Bars". AutoGuide.com. Retrieved 13 February 2023.
  6. 1 2 "Alloy Steel 6150 | Grade Summary". Metal Supermarkets. Retrieved 14 February 2023.
  7. ↑ "Chromium Vanadium Steel AISI 6150 – Boltport Fasteners". boltport.com. Retrieved 14 February 2023.
  8. ↑ "Simple Machines". ecampus.matc.edu. Retrieved 14 February 2023.
  9. ↑ "Torque and Rotational Motion Tutorial | Physics". physics.uoguelph.ca. Retrieved 14 February 2023.
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